This disclosure relates to the art of devices used for aspirating and dispensing small quantities of fluids. More particularly, the disclosure relates to a combination aspirating and dispensing device suitable for use with test devices having a sample containment region in the form of one or more wells or columns of wells, for example in the form of a multi-well plate.
Test devices in the field of biology and biochemistry can take a variety of forms, including devices arranged in an array of wells, such as an 8×12 array of wells arranged in rows and columns. In order to conduct a test on the sample the sample must be loaded into the well. A variety of dispensing devices are known in the art, and described in the patent literature. See, for example, U.S. Pat. Nos. 5,578,270; 6,374,683; 6,325,114; 6,537,505 and 6,983,636. Some of these dispensing devices are automated, while others require a human operator to manually dispense a sample into a well of a test device.
The assignee of this invention has developed a grating-based biosensor which can be affixed to the bottom of a bottom-less multiwell plate whereby the multiwell plate forms a receptacle for holding a biochemical sample to be tested. Grating-based sensors represent a new class of optical devices that have been enabled by recent advances in semiconductor fabrication tools with the ability to accurately deposit and etch materials with precision less than 100 nm.
Several properties of photonic crystals make them ideal candidates for application as grating-type optical biosensors. First, the reflectance/transmittance behavior of a photonic crystal can be readily manipulated by the adsorption of biological material such as proteins, DNA, cells, virus particles, and bacteria on the crystal. Other types of biological entities which can be detected include small and smaller molecular weight molecules (i.e., substances of molecular weight<1000 Daltons (Da) and between 1000 Da to 10,000 Da), amino acids, nucleic acids, lipids, carbohydrates, nucleic acid polymers, viral particles, viral components and cellular components such as but not limited to vesicles, mitochondria, membranes, structural features, periplasm, or any extracts thereof. These types of materials have demonstrated the ability to alter the optical path length of light passing through them by virtue of their finite dielectric permittivity. Second, the reflected/transmitted spectra of photonic crystals can be extremely narrow, enabling high-resolution determination of shifts in their optical properties due to biochemical binding on the surface of the grating while using simple illumination and detection apparatus. Third, photonic crystal structures can be designed to highly localize electromagnetic field propagation, so that a single photonic crystal surface can be used to support, in parallel, the measurement of a large number of biochemical binding events without optical interference between neighboring regions within <3-5 microns. Finally, a wide range of materials and fabrication methods can be employed to build practical photonic crystal devices with high surface/volume ratios, and the capability for concentrating the electromagnetic field intensity in regions in contact with a biochemical test sample. The materials and fabrication methods can be selected to optimize high-volume manufacturing using plastic-based materials or high-sensitivity performance using semiconductor materials.
Representative examples of grating-type biosensors in the prior art are disclosed in Cunningham, B. T., P. Li, B. Lin, and J. Pepper, Colorimetric resonant reflection as a direct biochemical assay technique. Sensors and Actuators B, 2002. 81: p. 316-328; Cunningham, B. T., J. Qiu, P. Li, J. Pepper, and B. Hugh, A plastic colorimetric resonant optical biosensor for multiparallel detection of label-free biochemical interactions, Sensors and Actuators B, 2002. 85: p. 219-226; Haes, A. J. and R. P. V. Duyne, A Nanoscale Optical Biosensor: Sensitivity and Selectivity of an Approach Based on the Localized Surface Plasmon Resonance Spectroscopy of Triangular Silver Nanoparticles. Journal of the American Chemical Society, 2002. 124: p. 10596-10604.
The photonic crystal biosensors of the assignee and associated detection instruments for label-free binding detection are also described in the patent literature; see U.S. patent application publications U.S. 2003/0027327; 2002/0127565, 2003/0059855 and 2003/0032039. Methods for detection of a shift in the resonant peak wavelength are taught in U.S. Patent application publication 2003/0077660. The above-references patent applications and articles are hereby incorporated by reference in their entirety.
There is currently a need in the art for simple, easy to use device which allows for simultaneous dispensing and aspirating of a solution containing a test sample onto a testing device, e.g., one configured in an array of wells. This invention meets that need.